I found some other threads discussing this issue, but I've not found any real solutions.

I recently picked up a 2017 C2 that, when shifting from 1 -> 2 at 7000rpm @ WOT would grind and not make it into gear. It wouldn't always happen, but it did it often enough. It would happen more often when the car was warm (which is odd). It ONLY happens during quick 1->2 shifts and only around 7000rpm. If I shift slowly, it will never occur, but what fun is that? Aside from this issue, the gearbox shifted fantastically.

I brought it to Porsche and was able to reproduce the issue for their service department. They replaced it with a "new" (remanufactured) trans under warranty, which I am grateful for.

I drove it for an hour or so that day without any grinding, however the new gearbox was very notchy/sticky since it wasn't broken in.

Today, I finally got around to taking the car out for a drive. While the shifter definitely loosened up and started feeling better, I unfortunately had it grind twice going into 2nd gear.

While the remanufactured trans that is now in my car MAY have been remanufactured for a 1->2 grind (I have no way of knowing whether it is or it isn't), I'm starting to think that it's not an issue with the transmission itself.

If it were a design flaw, you think it would happen to everyone.

Moreover, I found a thread where a guy had 3 different transmissions in his car, and they all had the same exact issue.

I wanted to start a thread to brainstorm and try to find a solution for this, especially since there seems like there are a fair amount of manual owners out there with the same issue. So in no particular order, here are my hypotheses:

1. Internally, these transmissions are internally a PDK with some added mechanisms to make them shift in a standard "H" pattern. The mechanism is called the MECOSA. The odd thing about the gear layout in the PDK is that 1st and 2nd gear aren't in the same gate like they are in a traditional manual. Rather, they are adjacent. Perhaps the fact that going from 1->2 requires the mechanism to move to a completely different gate during a fast shift makes it "hang up" sometimes.
2. Some cars have a clutch delay valve or a clutch pill from the factory. While they do tend to interfere with shifting, they usually slow down the clutch engagement rather than the disengagement. The engagement in my case is not the issue, since the grinding occurs with the clutch pedal on the floor, which SHOULD mean it's completely disengaged. It's possible though, that they have some similar mechanism that interferes with disengagement.
3. According to what I've found on the forums, the factory fluid for these transmissions is Mobilube PTX SAE 75W90. While a quick google search shows that people tend to like the fluid, many Mobil transmission fluids are sub-par to say the least. I'm half tempted to try some Neo 75-90HD, which I've had great results with over the years in other vehicles, but I'm not sure if it's compatible with this gearbox, and I'm worried that Porsche would void my warranty over it.
4. Perhaps there is some kind of issue with the shifter linkage?
5. Maybe there is some engine/trans lash in 1st gear which is throwing off engagement? If so, perhaps a stiffer engine/transmission mount would help?

Anyone have any other ideas?

Has anyone successfully fixed this issue in their car?

 

That sounds scary... Looks like you still have warranty on the car, and instead of speculating I'd take the car back to the dealer. First of all get a clear answer whether the transmission install was brand new or remanufactured.

You are already past the hard step, which is convincing that there is a problem, and they tried to fix it under warranty. Take the car back and tell them that the fix didn't work. This time it should be much easier. If that doesn't work again, you should probably invoke the lemon law.

 

I wouldn't try to blame the PDK. Just out of curiosity here are some details on PDK vs MT. First 2 gears are shared.

 

2-4 Would be the next step the dealer should be looking into, if they didnt already replace it with the new trans they swapped in.

5 would be something you can suggest as a last resort once 2-4 is done.


I agree with this, take it back and let them deal with it till its fixed to your liking or like new else theyll have to lemon it.

 

According to the tech who installed it, it was a reman. He mentioned something about there being a specific letter in the serial number which denotes that.

 

I have an appointment with the dealer for tomorrow morning, will keep you guys posted.

There's enough people with this issue where there should be some kind of "official" fix by now.

 

This can be discussed for days, weeks or months. There will be no correct answer. You should drive a pre owned MT car and see if it happens. Can it be your driving style? What rpm do you shift from 1 to 2.

Take it back to the dealer and log another service appt.

 

It is hard, but most importantly don't stress out, nerve cells regenerate very slowly. Just leave the car at dealer until its fully fixed.

Is this a CPO or original warranty? How much time until expiration?

Btw, it was smart comment to try out another used MT. Just find used one and go for a test drive to feel the difference. It would be fun to see sales rep's face when you redline on 1st gear

 

The issue occurs when shifting around 7000rpm.

I drove another 7mt on the lot and could not reproduce the issue on it.

 

Luckily it's CPO until May of '21.

I'm not losing sleep over it, I have other cars to drive, but I'm more just curious as to why this is occurring.

 

Ah I hate 2nd gear grinds. Both my BMW E92 M3 and F82 M4 6MT did that. I have no experience with Porsche MT, but I've heard others complain about this before. So you're not alone if you ask me.

 

Dealer bled the clutch line while I waited, no change in grinding.

 

my 991.1 has that issue that I made sure dealer documented in their system as my complaint. There are times 1st to 2nd is notchy or grindy whow ever you describe it.

This morning driving to work, didn't notice it much on revs to 3.5k with slow gear switching.

 

Did you report it under warranty?

 

Maybe grab the vin from that car and provide that to Porsche. Call Porsche and open a case. They might get a specialist involved. Having a vin from a car that doesn't do it might help then trace it back to a production lot.

Good luck.